In a wireless communication system, accurate channel estimation is often needed for accurate signal decoding. One particularly good channel estimation techniques includes a Minimum Mean Square Error (MMSE) channel estimation.
According to the MMSE channel estimation technique, channel estimation is initially performed based on Least Square (LS) and then the correlation matrix of a channel that varies along time and frequency axes is calculated on a channel basis. Since the MMSE channel estimation technique minimizes a total estimation error when taking noise into account, it generally performs well in a multi-path fading channel environment.
MMSE channel estimation is based on pilot tones of Orthogonal Frequency Division Multiple Access (OFDMA) symbols. Therefore, the performance of channel estimation may be degraded when performed with relatively small number of pilot tones. Accordingly, as many pilot tones as possible should be used to increase the performance of MMSE channel estimation.